The present invention is generally directed to vehicle systems that have sensor units that sense tire condition parameters, such as tire pressure and tire temperature. Specifically, the present invention relates to mounting arrangements for sensor units with tires.
Numerous tire condition monitoring systems have been developed in order to provide tire operation information to a vehicle operator. One example type of a tire condition monitoring system is a tire pressure monitoring system that detects when air pressure within a tire drops below a predetermined threshold pressure value.
There is an increasing need for the use of tire pressure monitoring systems due to the increasing use of xe2x80x9crun-flatxe2x80x9d tires for vehicles such as automobiles. A run-flat tire enables a vehicle to travel an extended distance after significant loss of air pressure within that tire. However, a vehicle operator may have difficulty recognizing the significant loss of air pressure within the tire because the loss of air pressure may cause little change in vehicle handling and little change in the visual appearance of the tire.
Typically, a tire pressure monitoring system includes tire-based pressure sensing components, tire-based components that provide communication links from the tires to a central receiver, and an indicator or display located on a vehicle instrument panel. In particular, the tire-based components of such a tire pressure monitoring system are provided in sensor units located inside the tires. In one known system, the sensor units transmit radio frequency signals that are received via stationary antennas that are located near the tires.
In one known system, each sensor unit is attached to an air valve. In turn, the valve is attached to an associated rim such that the sensor unit is inside the associated tire. At first glance, this solution is acceptable since the valve constitutes a convenient anchoring point. But this solution has a disadvantage of being complex from a mechanical viewpoint, particularly for fastening the valve and attached sensor unit onto the rim prior to assembly of the tire.
Another known system utilizes straps to attach the sensor units to the rims. Each strap encircles the associated rim and is tight against the rim. However, mechanical complexity may also be an issue for the use of straps.
In general, the present invention provides a tire sensor unit that is easy to assemble, handle, and mount within a tire, and that does not interfere with an inflation valve for the tire.
In accordance with one aspect, the present invention provides a sensor unit that senses at least one physical parameter of a vehicle tire mounted on a wheel rim. The sensor unit has an element that detects the parameter, electronics that generate radio frequency messages that convey the value of the parameter, an emitting element, such as an antenna, and a source of electrical energy. The invention has a characteristic in that the sensor unit is incorporated in a box placed inside the space delineated by the rim and the tire and is fastened by at least one pin that is permanently joined to the rim and that inwardly protrudes in a radial direction.
In accordance with another aspect, the present invention provides an arrangement for provision of vehicle tire sensory information while a tire is mounted on a wheel rim of a vehicle. The arrangement includes a sensor unit. The sensor unit includes a tire condition sensor, a signal transmitter, and a housing that contains the sensor and the transmitter. The housing has a mounting hole. A stud is welded to the rim and extends into the space bounded between the tire and the rim. The stud extends through the mounting hole of the sensor housing. A retainer extends between the sensor housing and the stud such that the sensor housing is held fixed relative to the stud.
In accordance with another aspect, the present invention provides a method of attaching a tire condition sensor unit to a rim of a vehicle tire assembly. The sensor unit senses a tire condition parameter and transmits a signal indicative of the sensed parameter. A stud is welded directly to the rim to extend into a space bounded by the rim and a tire of the tire assembly. The tire condition sensor unit is located adjacent to the welded stud. A retaining component is engaged between the welded stud and the tire condition sensor unit.